Comprehensive analysis of the human genome will provide sequences of between 30,000 and 50,000 genes. Many of these genes will not reveal function from their sequences. Recently Dr. Brent has extended his two hybrid technology by developing interaction mating techniques, which facilitate the assay of large numbers of individual binary protein-protein interactions. These techniques offer the possibility of extracting functional information from large numbers of genes in a way that does not depend on their sequence. During the next five years, two hybrid technology will be developed further, and used to analyze a set of several hundred human genes, involved in cell proliferation decisions. The end result of these experiments will be knowledge about the numerous genes involved in cell proliferation, and methods and reagents that can be scaled up further to yield significant information from other cDNAs encoded by humans and other model organisms. During the project, the investigator will add to the proteins to be tested new proliferation regulators from others and from his own work. Similarly, he will add to his existing panels of informative proteins (baits) new ones generated by his own work and solicited from other investigators, so that, by the end of the project, Dr. Brent will have greater than 3,000 baits of different functions. Techniques will be developed to facilitate the use of interacting proteins to guess genetic function, including new fusion protein, reporter gene, data collection, and algorithmic techniques. Finally, as a sample project, proteins in the test set will be assigned functions and there will be an attempt to order them within genetic pathways. The investigator will apply these techniques to identify altered regulators that may cause proliferative disorders. If successful, these experiments could have a number of favorable consequences. First, they will aid assignment of function to proteins of uninformative sequence, and thus contribute to many aspects of biology. Second, as a corollary of the first, they will aid the identification of target genes for gene therapy and pharmaceutical research. Third, they will aid assignment of function to hitherto genetically silent polymorphisms and allelic variants. Fourth, they will aid the identification of clusters of genes and allelic variants that work together to contribute to disease states and other genetic traits.